I have a 2 and a half year old car, that I use about 80miles a day in freeway miles.
Driving on the freeway, I occasionally end up behind trucks that are dropping gravel behind them, and I occasionally get a piece of gravel bouncing off my windshield.
The outside of my windshield has not a chip in it. All of the chips are appearing on the inside. These are small (think the writing end of a cheap ball point pen). So far, no cracking.
I’ve never seen chipping on the inside, from a blow to the outside. Is this normal? Is it a defect with the windshield? Are chips like this repairable, or should I wait until it starts cracking, then get it replaces?
I’ve seen this in a much more spectacular form in store windows near busy streets. Vehicles kicking up stones and gravel sometimes cause quarter-sized and larger cones of glass to be blasted from the inside of the window. It’s basically a transfer of momentum. You’ve seen the toy that sits on desk consisting of a number of metal balls suspended from wires? You pull one end ball and let it drop and the momentum gets transfered through all the balls, causing the opposite end ball to fly up. But the ones in the middle hardly move, if at all. Same principle.
Windshields are made with safety glass, designed to prevent them from shattering into many little pieces. But if you see a crack forming I wouldn’t wait too long, everyday driving has vibrations that could transfer to the crack and make it larger and larger.
I had a POS truck that had a crack on its windshield and I drove it for some time (6 mos or so). I don’t know about your state, but in mine, it’s illegal and you can’t pass an annual safety check in that condition.
I don’t know if pitting could eventually turn into a crack, but I suppose it is possible.